In Bohr's 1905 prize experiments, what liquid property did he investigate?

In Bohr’s 1905 prize experiments, he investigated the surface tension of liquids, especially by studying vibrations in a jet of water. The project began when the Royal Danish Academy of Sciences and Letters announced a competition based on Lord Rayleigh’s theory of liquid-jet vibrations.

Bohr was still a university student and worked in the laboratory of his father, Christian Bohr, a physiology professor. Because Copenhagen University lacked a suitable physics laboratory, he sometimes made observations at night to reduce disturbances from passing traffic. His work combined careful measurement with mathematical analysis of the oscillating jet.

The academy awarded Bohr its gold medal, and he later refined the research for publication. His 1908 paper on determining water’s surface tension by jet vibration became his first major scientific publication. This early experimental work is separate from his later fame for atomic theory, which began with his 1913 model of the atom.